#pragma once

#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <mutex>
#include <cassert>
#include <fstream>
#include <jsoncpp/json/json.h>


#include "../comm/log.hpp"
#include "../comm/util.hpp"
#include "../comm/httplib.h"
#include "oj_model.hpp"
#include "oj_view.hpp"

namespace ns_control
{
    using namespace std;
    using namespace ns_log;
    using namespace ns_util;
    using namespace ns_model;
    using namespace ns_view;
    using namespace httplib;

    //提供服务的主机
    class Machine
    {
    public:
        std::string ip; //编译服务的ip
        int port;       //编译服务的port
        uint64_t load;  //编译服务的负载
        std::mutex* mtx;//mutex是禁止拷贝的，使用指针来完成
    public:
        Machine():ip(""), port(0), load(0), mtx(nullptr) {}
        ~Machine() {}
    public:
        //提升主机负载
        void IncLoad()
        {
            if(mtx) mtx->lock();
            ++load;
            if(mtx) mtx->unlock();
        }
        //减少主机负载
        void DecLoad()
        {
            if(mtx) mtx->lock();
            --load;
            if(mtx) mtx->unlock();
        }

        void ResetLoad()
        {
            if(mtx) mtx->lock();
            load = 0;
            if(mtx) mtx->unlock();
        }
        //获取主机负载，没有太大的意义，只是为了统一接口
        uint64_t Load()
        {
            uint64_t _load = 0;
            if(mtx) mtx->lock();
            _load = load;
            if(mtx) mtx->unlock();
            return _load;
        }

    };

    const std::string service_machine = "./conf/service_machine.conf";
    //负载均衡模块
    class LoadBlance
    {
    private:
        //可以提供编译服务的所有主机
        //每一台主机都有自己的下标，用来充当当前主机的id
        std::vector<Machine> machines;
        //所有在线的主机id
        std::vector<int> online;
        //所有离线的主机id
        std::vector<int> offline;
        //保证LoadBlance的数据安全
        std::mutex mtx;
    public:
        LoadBlance() 
        {
            assert(LoadConf(service_machine));
            LOG(INFO) <<"加载 " << service_machine << " 成功" << "\n";
        }
        ~LoadBlance() {}
    public:
        bool LoadConf(const std::string& machine_conf)
        {
            std::ifstream in(machine_conf);
            if(!in.is_open())
            {
                LOG(FATAL) << "加载: " << machine_conf << " 失败" << "\n";
                return false;
            }
            std::string line;
            while(std::getline(in, line))
            {
                std::vector<std::string> tokens;
                StringUtil::SplitString(line, &tokens, ":");
                if(tokens.size() != 2)
                {
                    std::cout << "切分" << line << "失败" << "\n";
                    continue;
                }
                Machine m;
                m.ip = tokens[0];
                m.port = atoi(tokens[1].c_str());
                m.load = 0;
                m.mtx = new std::mutex();
                online.push_back(machines.size());
                machines.push_back(m);
            }

            in.close();
            return true;
        }
        bool SmartChoice(int* id, Machine** m)
        {
            //选择主机后，更改该主机的负载
            //可能需要离线该主机
            mtx.lock();
            int online_num = online.size();

            //std::cout << online_num << std::endl;

            if(online_num == 0)
            {
                mtx.unlock();
                LOG(FATAL) << "所有后端编译主机均离线，请运维尽快查看！" << "\n";
                return false;
            }

            //遍历找到所有机器中负载最小的那个
            *id = online[0];
            *m = &machines[online[0]];
            uint64_t min_load = machines[online[0]].Load();
            for(int i = 1; i < online_num; i++)
            {
                uint64_t curr_load = machines[online[i]].Load();
                if(min_load > curr_load)
                {
                    min_load = curr_load;
                    *id = online[i]; 
                    *m = &machines[online[i]];
                }
            }
            mtx.unlock(); 
            //std::cout << "走到这了" << std::endl;
            return true;
        }
        void OfflineMachine(int which)
        {
            mtx.lock();
            for(auto iter = online.begin(); iter != online.end(); iter++)
            {
                if(*iter == which)
                {
                    machines[which].ResetLoad();
                    online.erase(iter);
                    offline.push_back(which);
                    break;
                }
            }
            mtx.unlock();
        }
        void OnlineMachine()
        {
            mtx.lock();
            online.insert(online.end(), offline.begin(), offline.end());
            offline.erase(offline.begin(), offline.end());
            mtx.unlock();

            LOG(INFO) << "所有的主机有上线啦!" << "\n";
        }

        void ShowMachines()
        {
            mtx.lock();
            std::cout << "当前在线主机列表: ";
            for(auto& id : online)
            {
                std::cout << id << " ";
            }
            std::cout << std::endl;

            std::cout << "当前离线主机列表: ";
            for(auto& id : offline)
            {
                std::cout << id << " ";
            }
            std::cout << std::endl;
            mtx.unlock();
        }

    };

    //核心业务逻辑
    class Control{
    private:    
        Model model_;
        View view_;
        LoadBlance load_blance_;// 核心负载均衡器
    public:
        Control() {}
        ~Control() {}
    public:
        void RecoveryMachine()
        {
            load_blance_.OnlineMachine();
        }
        //根据题目数据构建网页
        //html：输出型参数
        bool AllQuestions(string* html)
        {
            bool ret = true;
            vector<struct Question> all;
            if(model_.GetAllQuestions(&all))
            {
                sort(all.begin(), all.end(), [](const struct Question& q1, const struct Question& q2){
                    return atoi(q1.number.c_str()) < atoi(q2.number.c_str());
                });
                //获取题目信息成功，将所有的题目数据构建成网页
                view_.AllExpandHtml(all, html);
            }
            else
            {
                *html = "获取题目失败，形成题目列表失败";
                ret = false;
            }
            return ret;
        }

        bool Question(const string& number, string* html)
        {
            bool ret = true;
            struct Question q;
            if(model_.GetOneQuestion(number, &q))
            {
                view_.OneExpandHtml(q, html);
            }
            else
            {
                *html = "指定题目：" + number + "不存在！！";
                ret = false;
            }
            return ret;
        }

        void Judge(const std::string& number, const std::string in_json, std::string* out_json)
        {
            //0.根据题目编号number，直接拿到对应的题目细节
            struct Question q;
            model_.GetOneQuestion(number, &q);
            //1.in_json进行反序列化，得到题目的id，用户提交的源代码以及input
            Json::Reader reader;
            Json::Value in_value;
            reader.parse(in_json, in_value);
            std::string code = in_value["code"].asString();
            //2.重新拼接用户代码+测试用例代码，形成新的代码
            Json::Value compile_value;
            compile_value["input"] = in_value["input"];
            compile_value["code"] = code + q.tail;
            compile_value["cpu_limit"] = q.cpu_limit;
            compile_value["mem_limit"] = q.mem_limit;
            Json::FastWriter writer;
            std::string compile_string = writer.write(compile_value);
            //3.选择负载最低的主机
            //差错处理规则：一直选择，直到有主机可用，否则就是全部挂掉
            while(true)
            {
                int id = 0;
                Machine* m = nullptr;
                if(!load_blance_.SmartChoice(&id, &m))
                {
                    break;
                }

                LOG(INFO) << " 选择主机成功， 主机id: " << id << " 详情： "<< m->ip << ":" << m->port << "\n";

                //4.然后发起http请求，得到结果
                Client cli(m->ip, m->port);
                m->IncLoad();
                if(auto res = cli.Post("/compile_and_run", compile_string, "application/json;charset=utf-8"))
                {
                    //5.将结果赋值给out_json
                    if(res->status == 200)
                    {
                        *out_json = res->body;
                        m->DecLoad();
                        LOG(INFO) << "请求服务器成功..." << "\n";
                        break;
                    }
                    m->DecLoad();
                }
                else
                {
                    //请求失败
                    LOG(INFO) << " 当前请求的主机id: " << id << " 详情： "<< m->ip << ":" << m->port << "可能已经离线！" << "\n";
                    load_blance_.OfflineMachine(id);
                    load_blance_.ShowMachines();//仅仅用来调试
                }
            }
        }

    };
}